Information and Advice

Electronic Speed Controllers

History:

The first true Electronic Speed Controllers were developed for brushed stock and modified motors in the late 1970s, early 1980s by companies like Tekin in the USA, LRP in Germany and Demon, a London based company in the UK. These bulky and comparatively heavy early ESCs used basic resistors, rheostats, capacitors, transistor switches for stepped acceleration and rectifiers for reverse operation, all crammed together on a simple circuit board. Although they were a vast improvement on the old cumbersome mechanical speedos of the time, they were still very jerky to control and prone to burn out if not carefully managed.
Throughout the 1980s and 1990s, each year brought improvements and with the help of the new FET (Field Effect Transistors) plus some basic mass produced integrated circuits, miniaturisation and reliability steadily improved.
By the mid 1990s, "regenerative breaking" to recharge the battery was developed, long before F1 had KERS (Kinetic Energy Recovery System) and adjustable anti lock breaking was becoming the norm.
With the introduction of Brushless Motors in the late 1990s early 2000s a new breed of ESC were developed to make the most of the new technology and ever improving Rechargeable Batteries. The latest ESC now use sensors to manage the motor and can be adjusted remotely for different conditions.

ESC for Brushed Motors.

Basic "Silver Can" Stock Motors that are usually supplied with RC model kits are easily satisfied by low current 5 Amps to 20 Amps ESC. However, Modified Brushed Electric Motors are very power hungry and need lots of Amps to feed on. ESC for these motors range from around 20 Amps to 340 Amps.
On many older models the setup of the ESC was done using a small screwdriver to adjust the trim and output punch but newer models use a simple one step push button system.
Higher spec ESC can be programmed to set the acceleration curve and breaking to suit your particular driving style.

ESC for Brushless Motors.

ESC for Brushless Motors are completely different to those for brushed motors and are not compatible in any way.
These ESC take the DC (Direct Current) input from the battery and transform it into three phase AC (Alternating Current). The three output "waves" go to each of the three wires on the Brushless motor. By changing the wavelength or frequency of the output wave the motor will spin faster or slower for acceleration and breaking. For reverse, any two of the three "phases" are simply switched.
Current ratings of Brushless Motor ESC, at the time of this article, can be anything from 3 Amps to around 300 Amps.
For beginners it is recommended that you buy an ESC and Motor Combo to ensure the Current rating for the ESC is correct for the Motor.

BEC (Battery Eliminator Circuit).

Many, but not all ESC have BEC to provide power for the Radio System without the need for a separate battery.

Hints and Tips

Radio Gear

How to avoid Interference.

1/ The first consideration when installing your Receiver into your Electrically Powered Model is to make sure it is well away from the Negative Battery terminal, and the Motor. The Magnetic field can cause stuttering type interference at times of high current draw (i.e., Fast Acceleration)

2/ Make sure the Ariel tube is long enough for the Ariel wire. The tip of this wire is highly sensitive and should be as high, and as far away from the Motor as possible (yup, its that magnetic field prob again)

3/ If all else fails, a simple tip that often works for all RC Model enthusiasts is to wrap the receiver in Aluminium Foil, to shield against any magnetic and external radio interference.

4/ As a last resort, to protect against servo twitch, try ferrite beads. (available at Radio Shack or Maplins) These are threaded over the red, white (or yellow) and black wires of each servo.

5/ If you are using a FET Servo, the installation of a choke (a small electrical component) in the positive feed wire will smooth out any current spikes and reduce the possibility of "servo twitch".

6/ Another thing you might try is a "glitch buster" or "stutter stopper". Basically, this is a capacitor that simply plugs into your Radio Receiver and attempts to keep a level voltage supply to the Radio system.